Speed control for liquefier



March 27, 1956 J. J. KUESER ET AL 2,740,029

SPEED CONTROL FOR LIQUEFIER Filed April 27, 1955 2 Sheets-Sheet l I L it Fl Z4? AZ. 2 //v VE/VTORS F (9. 9 JOHN J. KUESER 24 2 CHARLES 0. W505 \W 56 BYZY WWM "annu A TTOR/VEYS March 27, 1956 J. KUESER ET AL 2,740,029

SPEED CONTROL FOR LIQUEFIER Filed April 27, 1955 2 Shee ts-Shee t 2 ATTORNEYS United States Patent 2,740,029 SPEED CONTROL FOR LIQUEFIER John J. Kueser and Charles D. Visos, St. Louis, Mo., assignors to Knapp-Monarch Company, St. Louis, M0,, a corporation of Delaware Application April 27, 1953, Serial No. 351,280 Claims. (Cl. 201-62) This invention relates to a speed control for motor driven appliances such as liquefiers.

One object of the invention is to provide a speed controller which is combined with which the motor is housed.

Another object is to provide a control device of rheostat-like character to control the speed of the appliance in almost stepless fashion through a range from low to high, the design including an off position beyond the low speed end of the knob travel.

Another object is to operations such as food preparation notations when the appliance is a liquefier.

Still another object is to provide a combined rheostat and switch wherein a small projection in the base of the appliance cooperates with the speed control knob in such manner that a slider snaps from the extreme low-speed position to a position at the lower end of its travel where a double arc break occurs over a distance of some onethereby permitting operation of the appliance A further object is to provide a rheostat of special construction wherein fiber insulators or the like are provided at the off position of the slider so that carbon brushes carried thereby can pass across notches in these insulators wherein any loose particles of carbon may collect, thus preventing the spreading of such particles along the surface of the fiber to form a conductive path and along the turns of the resistance wires which would result in short-circuiting them.

Still a further object is to a nameplate with considerable indicia thereon as for different food preparations in relation to the speed of the motor at the various positions of the rheostat knob, the double resistance element arrangement providing one of side-by-side type wherein a slider with spring extended carbon brushes may slide in the space between them,

inafter more fully set forth, pointed out in our claims and illustrated in the accompanying drawings, wherein:

Figure 1 is a side elevation of a liquefier to which our present invention has been applied, portions of the liquefier being broken away and other portions being shown in section to illustrate the mounting of our control device in the base of the liquefier.

Figure 2 is a front elevation of a portion of the base showing the nameplate in association with our control device.

Figure 3 is an electro-diagrammatic view illustrating the circuit for the speed control.

Figure 4 is an inside elevation as taken on the line 4-4 of Figure l and shows the parts on an enlarged scale.

Figure 5 is a sectional view on the line 5-5 of Figure 4.

Figure 6 is a vertical of Figure 4.

Figure 7 is a horizontal sectional view on the line 7-7 of Figure 4.

Figure 8 is an enlarged sectional View on the line 8-8 of Figure 4 showing the slider in position adjacent the projection which produces snap action; and

Figure 9 is an enlarged sectional view on the line 99 of Figure 4.

On the accompanying drawings we have used the reference numeral 10 to indicate the base of a motor driven appliance wherein the motor is shown generally at 12. The appliance illustrated is a liquefier wherein a bowl 14 is adapted to receive materials to be liquefied by a rapidly rotating cutter blade 16. This blade is mounted on a shaft 18 connected by a coupling device 20 to the shaft 22 of the motor 12.

Our speed control device comprises a pair of insulation cores 24 (formed of porcelain or the like) suitably mounted in the base 10 as by clips 26 at their lower ends secured by screws 28 to bosses 30 in the base 10 (see Figure l) and by extending into sockets 32 of bosses 34 at their upper ends (see Figure 6).

Each of the cores 24 is Wound with a resistance coil 36. The ends of these coils are secured in clamp bands 38, 40, 42 and 44 and the clamp bands 40 and 44 serve as terminals for the resistance coils. Between the clamps the coils are covered with insulating cement 46 as shown in Figure 4 with the exception of their adjacent surfaces indicated at 48 with which it is desirable to make contact with carbon brushes 50 of a slider 52. The slider 52 consists of a tube (see Figure 7) carried in a bracket 54 and insulated therefrom by means of a sleeve 56.

The bracket 54, as shown in Figure 8, is secured by a rivet 58 to a corrugated strip-like support 60 adapted to slide along the inner surface of the base 10 back of a vertical slot 62 therein. Means is provided for effecting the sliding movement comprising a knob 64 exterior of the base having a reduced part 66 extending through the slot 62 and into a slot 68 of a corrugated spring 70. The corrugated strip 60 is also provided with a slot as indicated at 72 through which the part 66 extends. The parts just described are then held assembled by a cotter key 74 extending through an opening 76 of the extension 66.

On the outside of the base 10 we provide a nameplate 78 with a slot 80 through which the extension 66 also extends and this nameplate may be provided with indicia as shown in Figure 2 to indicate diiferent materials to be worked upon by the liquefier at the various corresponding speeds of the motor 12. The knob 64 cooperates with this indicia including off at the bottom of the nameplate as shown.

U-shaped fiber strips 82 extend partially around the cores 24 adjacent their lower ends as shown in Figures 4 and 9 and are held by the clamps 38 and 42 and by sectional view on the line 6-6 appiuss. of pe. r the. ike. .4. s. showninli sure. 4-

These strips are notched as indicated at 86 for a purpose which will hereinafter appear.

Thexireuiefor-the resistance'coils ,36, as shown in Figure 3,,is;in lseries with thefield coils 88 andthe-armature 9fl-of themotor 112.. The coils 3.6,- bridged by the-brushes 50yand the slider 52, constitute a rheostat-for varying, the Obviously when the-brushes 56- amount of resistance wire in tliecircuit of the motor-the higher the brushes, the less wire and therefore the less resistance. and the higher the motor speed.

We provide for snap action ofthe brushes to the ofi? position by meansof a projection 92'on the inside of the hase;10.:which, as shown in Figure 8, will'retard the down ward movement of the slider 52 and the brushes 50 as the knob 64 is pressed downwardly as indicated by the arrow 94.

Figure-1 shows the oft positionand the normal shape of the corrugated spring 70. Figure 8 shows this spring tensioned because the corrugated strip 60 is stopped by the projection 92 while the knob 64 has been pressed farther downward. The brushes 50 are still in contact with the coils 36, but as the knob 64 is pressed further, the lower end of the corrugated strip 60 will snap over the projection 92 and the corrugated spring 70 will spring to its initial shape shown in Figure 1 and in so doing will quickly move the brushes downwardly off the coils 36 and onto the fiber strips 82, the movement being some one'half' inch or so and also providing a double break for minimizing the arc and permitting the use of direct current. This is an important consideration in appliances of this type designed for either A. C. or D. C. operation as the problem of arcing at the time of turning the current oif is greater with D. C. than with A. C.

The notches 86 are provided to catch any carbon dust that might be on the brushes 50 and prevent it from being smeared across the fiber 82 where it would form a conducting path. The notches also prevent short-circuitin-g the turns of the resistance coils 36. These notches, accordingly, contribute to the efficiency of the slider as an off switch for the appliance in addition to being part of the rheostat.

Some changes may be made in the construction and arrangement of the partsof our speed controlfor liquefier without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims any modified forms of structure or use of mechanical equivalents which maybe reasonably included within their scope.

We claim as our invention:

1. In a speed control for a motor driven appliancehaving a base, an elongated resistance element mounted vertically in said base, said base having a vertical slot, at slider'movable along said resistance element, means for moving said slider, said means extending through-said slot to the exterior of said base, a control' -knobon said'means, one position of said slider being out of contact with said resistance element when said knob is at an endposition of limiting movement for de-energizing the motor of said appliance, and means to impart snap action to said slider between its position contacting said end of'said resistance element and the out-of-contact position thereof.

2. A speed controlfor-a motor driven appliance having a base comprisinga vertically elongated'resistanceelement' mounted. in. said base, said base having a vertical slot, a slider movable along said resistance element, means for moving said slider extending through said slot to the ex-. tetiorof; saidbase, acontrol knob on saidmeans, one posts tion of said slider being out of contact with said resistance element at.a.. im. .ting. pesitiqnb y nd theturns-of. one. end,

thereof for de-energizing the motor of said appliance, said resistance element being provided with a covering of fiber or the like at said limiting position of said slider, said covering being provided with a notch in which the material of said slider may lodge to prevent. it from short-circuiting the turns of said resistance element, and means to impart snap action to said slider adjacent. the saidlimiting position thereof.

3. A speed control for a motor driven appliance having a base comprising a pair of elongated'resistance elements mounted vertically in said base, said base having a slot between them, a slider movable alongsaid'resistance elements and having carbon brushes for contacting the resistance elements, means for moving said slider extending through said slot to the exterior of said base, a control knob on said means, one position of said slider constituting an olf position adapted to de-energize the motor ofsaid appliance, said resistance elements,- atthe olfpositionof said slider, being provided with coverings of fiberor the like provided with notches in which the carbon ofthebrushes of said slider may lodge to prevent such carbon from short-circuiting the turns of said resistance elements.

4. In a speed control for a motor driven appliancehaving a base, an elongated resistance element mounted vertically in said base, said base having a slot, a carbon slider movable along said resistance element, means formoving said slider extending through said slot to the exteriorof said base, a control knob on said means, one position of said slider being out of contact with said resistance element at a position below said resistance coilconstituting an ofi" position adapted to de-energize the motor of said appliance, said coil at said ofi position of said slider being provided with a covering of fiber or the like provided with a notch in which the carbon of said slider may-lodge to prevent such carbon fromishortrcircuiting the-turns of said resistance element, means to impart snap action to said slider comprising a resilient connection between said slider and. said control knob, and a projection engaged by said slider for tensioning said resilient connection and then efiecting snap-over of said means inrelatiorrtosaid projection to result in quick movement of said slider away from the end of said resistance element andtoward said. off position.

5. In a speed controlfor a motor driven appliance hav.- ing a base, an elongated resistance element mounted vertically in said base, said base having'a vertical, slot, a slider movable along said resistance element, means for moving saidjslider, said means extending through said slot to the exterior of said base, a control knob on said means, an ofi position for said slider outof contactwith said resistance element adapted to de-energize the motor of,

said appliance, and means to impart snap. action to said slider adjacent said off position comprising a resilient connection between said slider and said control knob, a projection on said base engaged by said' slider for tensioning said resilient connection and then effecting snap over of said means in relation to said projection and resulting in quick movement of said slider away from said.

resistance element to said ofi position.

References Cited in the file of this patent UNITED STATES PATENTS 416,632 Leber Dec. 3, 1889 803,453 Stevens Oct. 31, 1 905 822,312 Stevens June 5, 1906 1,225,227 Dunharn May, 8, 1917 1,433,740 Nagel Oct. 31,192 1,489,182 Weinberg Apr. 1, 1924 2,103,922 Van Guilder Dec; 28, 1937 2,262,912 Behar Nov. 18, 1941 

